fix(NotificationContext): handle user ID for notifications fetching and prevent stale responses

src/contexts/NotificationContext.jsx

@@ -49,14 +49,20 @@ export function NotificationProvider({ children }) {
   const { user } = useAuth();
   const [notifications, setNotifications] = useState([]);
   const [unreadCount, setUnreadCount] = useState(0);
+  const activeUserId = useRef(null);
   // Track seen IDs to detect genuinely new arrivals and show toasts
   const seenIds = useRef(new Set());
   const initialized = useRef(false);
 
   const fetch = useCallback(async () => {
-    if (!user) return;
+    const requestUserId = user?.id;
+    if (!requestUserId) return;
     try {
       const res = await api.get('/notifications');
+
+      // Ignore stale responses that arrived after logout or account switch.
+      if (activeUserId.current !== requestUserId) return;
+
       const incoming = res.data.notifications || [];
       setNotifications(incoming);
       setUnreadCount(res.data.unreadCount || 0);
@@ -106,6 +112,7 @@ export function NotificationProvider({ children }) {
   }, []);
 
   useEffect(() => {
+    activeUserId.current = user?.id ?? null;
     if (!user) {
       setNotifications([]);
       setUnreadCount(0);